ML20053D719
| ML20053D719 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/02/1982 |
| From: | Vincent R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-15-19, TASK-RR NUDOCS 8206070247 | |
| Download: ML20053D719 (5) | |
Text
{{#Wiki_filter:1 e Consumers power Company General Offices: 212 West Michtgen Avenue. Jackson. Mkhleen 40201 * (517) 798 4650 June 2, 1982 Dennis M Crutchfield, Chief Operating Reactors Branch No 5 Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - SEP TOPIC XV-19, LOSS OF COOLANT ACCIDENTS RESULTING FROM SPECTRUM OF POSTULATED PIPING BREAKS WITHIN THE REACTOR COOLANT PRESSURE BOUNDARY (RADIOLOGICAL PORTION) By letter dated July 1, 1981, Consumers Power Company submitted to the NRC an evaluation of SEP Topic XV-19 for the Big Rock Point Plot. Subsequent discussions with the staff indicated that there were numerous questions about the analysis, and a request was made for further information. As a result of that request Consumers Power Company has reevaluated the site boundary doses following a LOCA using current methodology and criteria. A l description of that analysis and the results are attached. It should be specifically noted that this analysis is a typical conservative analysis for I licensing purposes. It is not considered to be a realistic representation of the doses which might be expected following a postulated LOCA. i n s [70-{7 I U2II Robert A Vincent Nuclear Licensing Administrator t $g l CC Administrator, Region III, USNRC / j NRC Resident Inspector-Big Rock Point O II pages l l l i 9206070247 920602 PDR ADOCK 05000155 P PDR
-o Big Rock Point Plant Systematic Evaluation Program SITE BOUNDARY DOSE FROM LOCA INSIDE CONTAINMENT En I L
~1 4 Big Rock Point Plant Systematic Evaluation Program j Site Boundary Dose from LOCA Inside Containment l \\ Summary of Results The results of the Loss of Coolant Accident Site Boundary dose analysis for Big Rock Point is as follows: Dose to thyroid due to inhalation over 2 hours - 8h.9 Rem (no spray or deposi-tion outside contain-ment) Dose to thyroid due to inhalation over 2 hours h5.7 Rem (with spray and deposi-tion outside contain-ment) Dose to whole-body over 2 hours - 1.66 Rem (infinite cloud) Dose to whole-body over 2 hours - 0.2 Rem (finite cloud) Discussion The event analyzed is an instantaneous double-end.ed rupture of the recircula-tion pump discharge pipe. Containment leakage is assumed at the limits set in the Technical Specifications (0 5% per day at design conditions). For con-servatism (and to follow Reg Guide 1.3) the leak rate was set constant at 0.5%/ day and the duration was 2h hours. The duration was chosen to be that for FRR's as Big Rock Point containment much more resembles a FWR containment rather than a BWR containment. The containment sprays were-assumed to fune-tion although its effect in reduction of the release iodine concentration to the containment atmosphere was not considered. Fission product inventory is l based on steady state operation at 2h0 MWt. The quantity of released fission products is consistent with Regulatory Guid'e 1.3, 100% of the noble gases, 25% of the iodines and 1% of the particulates. The quantity of fission pro-ducts available for release was obtained from the ORIGEN code output found in l l NEDO-2h782 (BWR Owners Group NUREG-0578 Implementation). Radiation doses were calculated for an infinite cloud model during the initial 2 hours into the l event since the Prompt Notification System installed at Big Rock Point vill re-sult in evacuation prior to that time if conditions varrant. . Credit was taken for the deposition of particulate and elemental iodine onto cooler surfaces using the following equations (presented in WASH-lh00 Appendix VII and Appendix J)
- 1. E V
Where: 1 is removal rate constant for natural deposition (mass transfer) A Surface area for mass transfer V for volume of,pontainment K = D(0.13 (GrSc)73 ) L
2 D = diffusivity of iodine in air i = lensth of mass transfer surface 3 Gr = 1 g (T ' surface - T gas)/(U/0)2T gas y = viscosity p = density g = acceleration of gravity Sc = U/DD 'A was found to be 1.85 I using average conditions over the 2h hours of release ( A would have been greater had only the first two hours been considered due to greater air to surface temperature differences). The whole-body and thyroid doses were obtained using the average Curies per second released over the two hour interval which is given by: [' Icfmg' T1 'e 7200a 1_' 1 7 0 se released "l 6 3 Where: cfmL = leak rate in ft / min corresponding to 0.5%/ day Vc = containment free volume 7200 = see in two hours a=cNL + A decay + A deposition 60Ve A decay = decay constant for the isotope A deposition = removal rate constant for natural deposition A dep = 0 for noble gases and methyl iodine C(0) = curies released at t = 0 The X/Q was taken from Reg Guide 1.3, ground level release assuming Pasquill F conditions. The doses were calculated at the side boundary 1/2 bile away. The equation for calculating whole-body dose was obtained from Reg Guide 1.3. Inhalation dose to the thyroid due to iodines was obtained from the following: IBreathing'I 1 f Ci 'I [I see released Q DCF D= rate A'2 hours IL 1 IL average dL Where: D = dose, rem 3 3 Breathing Rate = 1.25 m /hr from TID-lh8hh = 10 m /8 hr day Ci see released = average Curies per second released average DCF = Dose Conversion Factors, Rem /Ci from TID-lh8hh X[Q=AtmosphericDispersionfactorforgroundlevelrelease including building vake correction factor. The removal rates for containment spray and deposition once outside containment was not considered in obtaining the dose rates. If these were included, the doses vould be reduced by a factor of 1.86. This factor was determined by
- 1) obtaining a removal rate (1.11 hr-1) due to deposition outside containment; assuming free fall of particles 5 microns in diameter (particle size from WASH-1h00) and average height of the plume and 2) using a spray removal rate (10.k2 hr 1) given in NRC SER to Palisades Amendment 31, page 25 Credit was also not taken for l
elevated release. Leakage out of containment vill in most cases be into the turbine
u .f ' 3 ~ ),s l building or service building and therefore be carried to the stack with normal ventilation. Assuming elevated release would lower the doses about an addi-tional factor of 3 5., Leakage from the MSIV ana;ESF systems was considered negligible as compared to containment leakage because in our response to NUREG-0737 Item III.D.L1. (let-ter from Hilffman to Ziemsn of December 19, 1980) CPCo concludes that based on ~ a review of plant systems design, operating experience and operating procedures, no unknown radioactivity release paths were identified. There were five in-stances of inadvertant release. These instances resulted either from component failure for which corrective action has been taken to prevent recurrence, or from administrative deficiencies, which were promptly corrected. h. s e f $? O r y e O 09 g-s r* f - l s g 6 e 9 2 k ~ 1 b ' sI 9-n W V s s. I}}